src/darker/help.py:28: in <module>
    import flynt
flynt/__init__.py:7: in <module>
    from flynt.cli import main
flynt/cli.py:11: in <module>
    from flynt.api import fstringify, fstringify_code
flynt/api.py:14: in <module>
    from flynt.code_editor import (
flynt/code_editor.py:17: in <module>
    from flynt.transform.transform import transform_chunk
flynt/transform/transform.py:9: in <module>
    from flynt.transform.FstringifyTransformer import fstringify_node
flynt/transform/FstringifyTransformer.py:8: in <module>
    from flynt.transform.percent_transformer import is_percent_stringify, transform_binop
flynt/transform/percent_transformer.py:217: in <module>
    ast.Str,
E   AttributeError: module 'ast' has no attribute 'Str'